Florian Gassmann (03/05/1729 - 20/01/1774), a Bohemian (born in Most [Brüx], Bohemia, died in Vienna) conductor, composer and teacher of e.g. Antonio Salieri. He wrote operas, about 50 compositions for the church, symphonies, sonatas, etc.

In this period (19th century), there was nothing unusual in performing incomplete or fragmentary church works; for example, the uncompleted Requiem of Florian Leopold Gassmann, with additions from Joseph Krottendorfer as well as Father Joseph Kaintz, remained in the repertory of the Hofburg chapel well into the first half of the nineteenthh century.

From the late 17th century onwards, mainly through the contributions of leading opera composers such as Feo, Galuppi, Hasse, Pergolesi, Jommelli, Gassmann, Cimarosa and Gossec, individual movements of the requiem became gradually larger, the orchestration richer and the solo vocal writing more elaborate. In some cases, single texts, usually the sequence and the responsory, were set separately, either as independent motets or as a means of providing vivid contrast within chanted forms of the funeral service. Preceding Mozart's Requiem more immediately, and possibly influential upon it, are the settings by Michael Haydn (1771; D-Bsb) and F.L. Gassmann (1774; "Introit" and "Kyrie" only), both of them links in a continuing Viennese tradition. One of the most striking features of Haydn's setting is the use in the "Te decet hymnus" of a theme based on the appropriate plainchant melody; Mozart, in contrast, used the tonus peregrinus associated with Psalm cxiii.